cpufreq: OMAP: Add SMP support for OMAP4+

On OMAP SMP configuartion, both processors share the voltage
and clock. So both CPUs needs to be scaled together and hence
needs software co-ordination.

Also, update lpj with reference value to avoid progressive error.

Adjust _both_ the per-cpu loops_per_jiffy and global lpj. Calibrate
them with with reference to the initial values to avoid a
progressively bigger and bigger error in the value over time.

While at this, re-use the notifiers for UP/SMP since on UP machine or
UP_ON_SMP policy->cpus mask would contain only the boot CPU.

Based on initial SMP support by Santosh Shilimkar.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
[khilman@ti.com: due to overlap/rework, combined original Santosh patch
                 and Russell's rework]
Signed-off-by: Kevin Hilman <khilman@ti.com>

1 files changed, 71 insertions, 10 deletions

diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
index a6b2be7ea5a9..1953f9d082ad 100644
--- a/drivers/cpufreq/omap-cpufreq.c
+++ b/drivers/cpufreq/omap-cpufreq.c
@@ -23,9 +23,11 @@
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/opp.h>
+#include <linux/cpu.h>
 
 #include <asm/system.h>
 #include <asm/smp_plat.h>
+#include <asm/cpu.h>
 
 #include <plat/clock.h>
 #include <plat/omap-pm.h>
@@ -35,6 +37,16 @@
 
 #define VERY_HI_RATE    900000000
 
+#ifdef CONFIG_SMP
+struct lpj_info {
+        unsigned long   ref;
+        unsigned int    freq;
+};
+
+static DEFINE_PER_CPU(struct lpj_info, lpj_ref);
+static struct lpj_info global_lpj_ref;
+#endif
+
 static struct cpufreq_frequency_table *freq_table;
 static struct clk *mpu_clk;
 
@@ -60,7 +72,7 @@ static unsigned int omap_getspeed(unsigned int cpu)
 {
         unsigned long rate;
 
-        if (cpu)
+        if (cpu >= NR_CPUS)
                 return 0;
 
         rate = clk_get_rate(mpu_clk) / 1000;
@@ -71,7 +83,7 @@ static int omap_target(struct cpufreq_policy *policy,
                        unsigned int target_freq,
                        unsigned int relation)
 {
-        int ret = 0;
+        int i, ret = 0;
         struct cpufreq_freqs freqs;
 
         /* Ensure desired rate is within allowed range.  Some govenors
@@ -81,22 +93,57 @@ static int omap_target(struct cpufreq_policy *policy,
         if (target_freq > policy->max)
                 target_freq = policy->max;
 
-        freqs.old = omap_getspeed(0);
+        freqs.old = omap_getspeed(policy->cpu);
         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
-        freqs.cpu = 0;
+        freqs.cpu = policy->cpu;
 
         if (freqs.old == freqs.new)
                 return ret;
 
-        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+        /* notifiers */
+        for_each_cpu(i, policy->cpus) {
+                freqs.cpu = i;
+                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+        }
 
 #ifdef CONFIG_CPU_FREQ_DEBUG
         pr_info("cpufreq-omap: transition: %u --> %u\n", freqs.old, freqs.new);
 #endif
 
         ret = clk_set_rate(mpu_clk, freqs.new * 1000);
+        freqs.new = omap_getspeed(policy->cpu);
+
+#ifdef CONFIG_SMP
+        /*
+         * Note that loops_per_jiffy is not updated on SMP systems in
+         * cpufreq driver. So, update the per-CPU loops_per_jiffy value
+         * on frequency transition. We need to update all dependent CPUs.
+         */
+        for_each_cpu(i, policy->cpus) {
+                struct lpj_info *lpj = &per_cpu(lpj_ref, i);
+                if (!lpj->freq) {
+                        lpj->ref = per_cpu(cpu_data, i).loops_per_jiffy;
+                        lpj->freq = freqs.old;
+                }
+
+                per_cpu(cpu_data, i).loops_per_jiffy =
+                        cpufreq_scale(lpj->ref, lpj->freq, freqs.new);
+        }
 
-        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+        /* And don't forget to adjust the global one */
+        if (!global_lpj_ref.freq) {
+                global_lpj_ref.ref = loops_per_jiffy;
+                global_lpj_ref.freq = freqs.old;
+        }
+        loops_per_jiffy = cpufreq_scale(global_lpj_ref.ref, global_lpj_ref.freq,
+                                        freqs.new);
+#endif
+
+        /* notifiers */
+        for_each_cpu(i, policy->cpus) {
+                freqs.cpu = i;
+                cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+        }
 
         return ret;
 }
@@ -105,6 +152,7 @@ static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
 {
         int result = 0;
         struct device *mpu_dev;
+        static cpumask_var_t cpumask;
 
         if (cpu_is_omap24xx())
                 mpu_clk = clk_get(NULL, "virt_prcm_set");
@@ -116,12 +164,12 @@ static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
         if (IS_ERR(mpu_clk))
                 return PTR_ERR(mpu_clk);
 
-        if (policy->cpu != 0)
+        if (policy->cpu >= NR_CPUS)
                 return -EINVAL;
 
-        policy->cur = policy->min = policy->max = omap_getspeed(0);
-
+        policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu);
         mpu_dev = omap2_get_mpuss_device();
+
         if (!mpu_dev) {
                 pr_warning("%s: unable to get the mpu device\n", __func__);
                 return -EINVAL;
@@ -141,7 +189,20 @@ static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
 
         policy->min = policy->cpuinfo.min_freq;
         policy->max = policy->cpuinfo.max_freq;
-        policy->cur = omap_getspeed(0);
+        policy->cur = omap_getspeed(policy->cpu);
+
+        /*
+         * On OMAP SMP configuartion, both processors share the voltage
+         * and clock. So both CPUs needs to be scaled together and hence
+         * needs software co-ordination. Use cpufreq affected_cpus
+         * interface to handle this scenario. Additional is_smp() check
+         * is to keep SMP_ON_UP build working.
+         */
+        if (is_smp()) {
+                policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+                cpumask_or(cpumask, cpumask_of(policy->cpu), cpumask);
+                cpumask_copy(policy->cpus, cpumask);
+        }
 
         /* FIXME: what's the actual transition time? */
         policy->cpuinfo.transition_latency = 300 * 1000;